Abstract:
The influence of alkaline medium and ultraviolet irradiation on the fluorescence of solutions of carbon dots based on the laser dye Nile red has been studied. It was found that the increase in pH of the medium leads to the quenching of the red emission band dominant in the fluorescence spectrum of carbon dots and to the enhancement of the green band, and the same fluorescence behavior is characteristic of Nile red solutions. It is shown that the quenching of red fluorescence of carbon dots and Nile red is accompanied by a significant weakening of the corresponding bands in the absorption spectra of the fluorophores studied. A similar effect was observed in the fluorescence of solutions of carbon dots and Nile red with neutral pH $\sim$7 as a result of their irradiation with ultraviolet light in the spectral range of 248–400 nm. The influence of alkaline environment and ultraviolet irradiation on the optical characteristics of fluorophores is attributed to the chemical and photochemical reactions initiated by these external factors in the systems studied. The possible nature of the emissive centers involved in the reactions is discussed.
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